Heat oil, and cook onion and garlic until soft. Stir in broth, tomatillos, tomatoes, chilies, and spices. Bring to a boil, then simmer for 10 minutes. Add corn, chicken, and beans, and simmer 5 minutes. Season with salt and pepper to taste. Serve with these toppings for people to choose from: limes, cilantro, cheese, avocado, sour cream, and tortilla chips.